There are known various shapes of tablets. One of them is a tablet which is longer in one direction when seen in plan (for example, see Patent Literature 1). Concrete examples of them are a substantially rectangular tablet (51) having smooth corners when seen in plan as shown in FIG. 4(a), a standard elliptical tablet (53) having its both ends (52) formed by semi-circles each of which has a diameter of a tablet width (W) when seen in plan as shown in FIG. 4(b) and a substantially oval tablet (55) having its side edges (54) each formed in the shape of a smooth arc (hereafter referred to as an ‘oval tablet’).
Among them, the oval tablet (55) has a side edge (54) formed by an arc having a radius (R1), for example, about 1.5 times a tablet length (L), to which an end arc having a further smaller radius (R2) is connected smoothly so as to form an end portion (52). This oval tablet (55) has only a projected area of about 80% when compared with a rectangular tablet (56) having a width (W) and a length (L) (see FIG. 4(c)). So in order to keep the volume of this oval tablet large, it is necessary, for example, to increase the thickness of the tablet when compared with the standard elliptical tablet (53). However, there was a problem that if the thickness of the tablet is increased, the tablet could hardly be swallowed when it was dosed.
On the other hand, as for the substantially rectangular tablet (51) and the elliptical tablet (53) when seen in plan, the projected area is large in plan view. For example, in the case of the standard elliptical tablet (53), usually, the projected area is about 86% to 90% with respect to the rectangular tablet (56) (see FIG. 4(b)) having the width (W) and the length (L), although it may be different depending on the ratio of the width to the length. Further, as to the substantially rectangular tablet (51) when seen in plan, apparently, the ratio of its projected area is much higher. Thus as for these tablets, it is possible to easily retain the volume large without increasing the thickness of the tablet and the like dimension.
However, each of these substantially rectangular tablet (51) and the elliptical tablet (53) has a long linear portion at a side edge (54) in plan view, so that when it is subjected to the film-coating treatment, the long linear portion of this side edge (54) sticks to the other tablet through a coating agent to produce a so-called “twinning” defective product (hereafter referred to as “twin tablet”), which entails a problem of being not easy to improve the yield. Here, the twinning defective product also includes a defective product comprising at least three tablets mutually stuck.
Patent Literature 1: Utility Model Application Laid-Open No. 5-37924